This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. The following descriptions and examples are not admitted to be prior art by virtue of their inclusion in this section.
After a wellbore is drilled, a casing is often put in place to prevent the collapse of the wellbore and to facilitate aspects of completion and production. In these situations, the casing is cemented in order to seal an annulus between the casing and a formation there around. Determining integrity of the wellbore, or how well the cement has sealed the annulus, is a vitally important consideration for safety and efficient operations at a well site.
A sonic logging has been around since the 1960s and is well known to the oil field industry. An ultrasonic logging predates 1991. Both sonic and ultrasonic measurements are highly suitable and have been commonly used to facilitate the determination of acoustic impedance of the barrier material (for the purposes of discussion, the barrier material will be described as cement, but the disclosure should not be limited to the cement) in the annulus behind the casing. The acoustic impedance aids in providing an assessment of the hydraulic isolation produced by the barrier. Typically, the cement behind the first casing (in the 1st annulus) is the only barrier evaluated. The known techniques do not allow or otherwise prevent a robust evaluation of the barrier such as cement behind the 2nd (or more) casing.